The present disclosure generally relates to migrating logical partitions (or virtual machines), and more specifically, to techniques that allow for migrating logical partitions with an inactive input/output (I/O) server on a host computing system.
Administrators often logically partition the resources of computing systems through virtualization. These resources can include processors, memory, I/O devices, storage, etc. A firmware layer (e.g. a hypervisor) is used to expose virtualized computing hardware to different logical partitions (or virtual machines). Each logical partition can run a different operating system (OS). The hypervisor can provide each OS with a set of virtualized computing hardware. Referring in particular to I/O, a computing system may be provided with a special logical partition for I/O virtualization, referred to herein as a virtual I/O server (VIOS). A VIOS is generally configured to provide virtual I/O resources to the logical partitions of a computing system and enable shared access (by the logical partitions) to physical storage resources, e.g., disks, tape, optical media, etc.
Further, administrators, in some cases, may initiate a mobility event for a logical partition(s), which can include migration of the logical partition(s) from one source (host) computing system to another target computing system. Such a mobility event can occur during times of maintenance, for load-balancing, failure management, etc. One type of a migration process is an inactive migration, in which the logical partition from the source computing system is first powered off and then moved to the target computing system. Once moved, the logical partition can be powered on and activated. Another type of a migration process is an active migration, in which the migration of the logical partition is performed while service is provided and without disrupting user activities. In other words, the running logical partition (including its operating system and running applications) is moved from the source computing system to the target computing system without any shutdown or disruption of the operation of the running logical partition.
Typically, the migration of a logical partition or virtual machine from one (source) computing system to another (target) computing system involves frequent interaction with the VIOS partition on the source computing system. Thus, in cases where the source VIOS is inactive (e.g., due to errors or other issues), the migration of the logical partition from the source to the target computing system may not be possible until the source VIOS is once again activated. The process of activating VIOS partitions, however, can cause significant downtime in the migration process. For example, the process of activating the VIOS partition can involve powering off the source computing system to repair hardware issues before activating the VIOS partition. Activating the VIOS partition in this manner, however, can cause downtime for the logical partitions/applications (used by a user) and thus can affect the transparency (e.g., from the perspective of the user) of active migrations of logical partitions.